The present invention relates to active hydrogen-containing compositions and to articles prepared therefrom. More particularly, the present invention relates to active hydrogen-containing compositions comprising an alkoxylated epoxy resin adduct and its use in the preparation of rigid polyurethane foams.
Polyurethanes are a highly versatile class of plastics which find use in a broad range of applications. The properties of various polyurethanes in many cases determine, and often limit, these applications. Thus, much research is directed toward improving the properties of different types of polyurethanes in order to better meet the needs of a specific end use. In particular, in the field of rigid polyurethane foams, improvements in physical properties, such as, for example, friability, K-factor, compressive strength and dimensional stability are highly sought.
Among numerous approaches to improve the physical properties of rigid polyurethanes, one has been the inclusion of epoxy resins in the reaction mixtures or modification of the polyol used to prepare the polyurethane foam. U.S. Pat. No. 4,309,532 to Cuscurida et al. is directed to modified aminopolyols which are prepared by the reaction of rigid foam polyol initiator having an active hydrogen functionality equal or greater than four, with one or more alkylene oxides, and amine and an epoxy resin. These modified aminopolyols may then be reacted with organic polyisocyanates to prepare rigid polyurethane foams according to the disclosure in U.S. Pat. No. 4,394,463 also to Cuscurida et al.
Further, Floyd in U.S. Pat. No. 4,696,771, discloses aminopolyols which are products of the reaction of N-substituted ethanolamine with a terminal epoxy-containing compound. These aminopolyols are particularly useful in reaction injection molding (RIM) applications.
Another approach includes the use of epoxy resin adducts and is disclosed by Hampson et al. in U.S. Pat. No. 3,238,273. That patent discloses polyurethanes containing a reaction product of an organic polyisocyanate and/or polyisothiocyanate with a polyoxyalkylene polyol or a polyester having terminal hydroxyl groups in the presence of an adduct of a glyoidyl ether and a primary or secondary amine.
Trott et al. in U.S. Pat. No. 3,781,235 discloses a foamable composition convertible into a rigid foam which consists essentially of an isocyanate terminated polyol-prepolymer, an epoxy resin, an inert blowing agent and a dicarbonyl stabilizer selected from, for example, aliphatic dicarboxylic acids and aliphatic dicarboxylic acid anhydrides.
Although the polyurethanes discussed above show improved mechanical and physical properties relative to polyrethanes prepared in the absence of above-mentioned aminopolyols and/or adducts, there is still a need for rigid polyurethane foams exhibiting substantially reduced friability, improved K-factor, and increased compression strength.
Thus, it would be most desirable in the art to prepare polyurethane compositions and foams from compositions which are easily processed and which exhibit enhanced physical properties, such as reduced friability while maintaining comparable K-factor and increased compressive strength from such formulations compared to prior art foams.